<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>nav</title>
</head>
<style>
    *{
        list-style: none;
        padding: 0;
        margin: 0;
    }
    .header{
        height:40px;
        line-height: 40px;
    }
    .center{
        width: 1090px;
        height: 40px;
        margin: 0 auto;
        background-color: yellow;
        position: relative;
    }
    ul li{
        float: left;
        margin-right: 20px;
    }
    ul li div{
        height: 300px;
        width: 1090px;
        border: 3px solid #333;
        position: absolute;
        left: 0;
        display: none;
    }
    ul li:hover div{
        display: block;
    }
</style>
<body>
    <div class="header">
        <div class="center">
            <ul>
                <li>
                    <span>首页</span>
                    <div>首页的全部内容</div>
                </li>
                <li>
                    <span>居家生活</span>
                    <div>居家生活的全部内容</div>
                </li>
                <li>服饰鞋包</li>
                <li>美食酒水</li>
            </ul>
        </div>
    </div>
</body>
</html>